A rhodamine-based chromogenic and fluorescent chemosensor for copper ion in aqueous media

A rhodamine-based chemosensor for copper ion, 1-(rhodamine B)lactam-thiosemicarbazide (I), was designed and synthesized. Compound I is a colorless, non-fluorescent compound and was synthesized via the one-step reaction of rhodamine B hydrazide with KSCN in acidic medium. Upon mixing Cu2+ in acetonitrile-water (30:70, v/v) solution, the spirolactam ring of I was opened, which resulted in the dramatic increases in both fluorescence and absorbance of the mixing solution. Based on this mechanism, a chromo- and fluorogenic chemosensor for Cu2+ was developed. The fluorescence and absorbance signal are linear with Cu2+ concentration in the range 0.2-4.0 mu mol L-1 and 0.5-10 mu mol L-1, respectively. (c) 2008 Elsevier B.V. All rights reserved.